query:how can i know if the pic has been damage?

[sheth_ka]

im experimenting with pic16f877a,led blinking..the first time i''ve tried it, it works good, then the next time it didnt..i dont know what happen?? the pic burner can still recognize the pic16f877a,it can also reprogram it and read what inside..is the pic16f877a is still in the good condition or is not:?: thanks in advance..

 

[jumper2high]

If you can program it and verify (read and compare) - it's 99.9999% fine. Something else in your circuit has failed.

If it fails during verify process (read data does not match what you intended to write), the MCU is dead.

 

[sheth_ka]

If you can program it and verify (read and compare) - it's 99.9999% fine. Something else in your circuit has failed.

wooh, its good hear that..yeah i could verify the pic and program it again..thanks!

 

[arbj]

programming an verifying check one aspect only.. for a complete you must also check all the I/Os in the PIC...

 

[sheth_ka]

programming an verifying check one aspect only.. for a complete you must also check all the I/Os in the PIC...

yeah, im also thinking that it might happen to pic,im not sure, but i think i accidentally supplied the pic with a voltage more than 5V..do you think this may cause the damage to the pic??..i really want to know what made the pic run abnormal, its just that i dont know how to test the i/o.

 

[malik_123]

you should write a simple program which output high on all the pins and then check it whether the pins are giving the 5 volts or not

by this u can verify that all pins are working or not .

 

[arbj]

an improvement on that is to make all the I/Os high wait for some time, then low again, repeat this process continuously, the I/O states could be checked on a scope. If you do not have a scope, then the time delay could be increased and LEDs connected (through a resistance) to each of the pins.

This way you can see if the LEDs flash.

PICs are tolerant upto 5.5V ...does the PIC become hot when powered through 5 V ???

 

[betwixt]

Reading this thread reminds me of a good example of how NOT to test a processor.

Many years a go, a company which I will not name wrote a program for testing microprocessors, I think it was a 6502 in this case but my memory isn't what it used to be. The processor was plugged into a simple circuit which was nothing more than a small RAM and and EPROM chip. The program in the EPROM told the processor to monitor one of its pins and drive the lines of it's data bus low in sequence each time the pin was toggled. It worked well except for one important failing - the test jig toggled the pin, looked for a low on say D0, toggled again and looked on D1 and so on but it worked just as well with the chip under test removed! They forgot to look for the pins going high as well.

Brian.

 

[sheth_ka]

check it whether the pins are giving the 5 volts or not

does it really output in exact 5V??my pic only gives an output close to 4V..not exactly 5V,does this means the pic is damage???:|

Added after 3 minutes:

PICs are tolerant upto 5.5V ...does the PIC become hot when powered through 5 V ???

No..